When a structure (work piece) including metal or nonferrous metal as a welding base material is welded, non-consumable electrode type gas shield arc welding, so-called gas tungsten arc welding (GTAW), such as tungsten inert gas welding (TIG welding), has been conventionally used.
In TIG welding, a TIG welding torch is generally used, welding is performed by generating an arc between a non-consumable electrode and a work piece, melting the work piece by heat of the arc, and forming a molten pool. In addition, welding is performed by emitting a shield gas from a torch nozzle surrounding the non-consumable electrode, and thereby blocking atmosphere (air) by the shield gas.
Below, one example of a TIG welding torch which has been generally used is explained referring to FIGS. 14A and 14B. Moreover, FIG. 14A is a side view of the TIG welding torch 100, and FIG. 14B is a cross section of a main section of the TIG welding torch shown in FIG. 14A.
As shown in FIGS. 14A and 14B, the TIG welding torch 100 mainly includes a non-consumable electrode 101 which generates an arc between the non-consumable electrode 101 and a work piece; a collet 102 which supports the non-consumable electrode 100 in a state where the non-consumable electrode 100 is inserted into the collet 102; a collet body 103 on the inside of which the collet 102 is held in a state of projecting the non-consumable electrode 101 from the front end side; a torch body 104 on which the collet body 103 is mounted; a torch nozzle 105 which is mounted on the collet body 103 in a state of surrounding the non-consumable electrode 101, and emits a shield gas toward a molten pool of a work piece generated by the arc; a front side gasket 106 which is disposed between the torch body 104 and the torch nozzle 105; a torch cap 108 which is mounted in a state of disposing a rear side gasket 107 between the torch body 104 and the torch cap 108; and a handle 109 on which the torch body 104 is mounted and which a user holds.
When the TIG welding torch 100 explained above is used, welding is performed by connecting a welding cable C, emitting a shield gas, which is supplied from the welding cable C, from the torch nozzle 105 while generating an arc between the non-consumable electrode 101 and the work piece by electric power supplied from the welding cable C.